A power management method that divorces multicast frames for power save stations from DTIM beacons. An access point associates power save stations with a multicast group. Each station has an associated power save interval, the station being in a power save state during the interval, otherwise in an active state. The access point maintains a timer for each station in order to determine whether the station is in an active or power save state. The timer can be reset whenever the station sends an inbound frame. When the access point receives a multicast frame for the group, it buffers the frame until the timer for each member of the group expires, thereby ensuring each member of the group is in an active state, and broadcasts the multicast frame.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of power management for a network, comprising: associating a plurality of stations with a multicast group, wherein the plurality of stations associated with the multicast group comprises a first station with a first power save interval and a second station with a second power save interval that is independent from the first power save interval, wherein the first and second stations wakeup at unscheduled times; maintaining a plurality of separate timers corresponding to the plurality of stations, each timer of the plurality of timers corresponding to the power save interval of a one of the plurality of stations; individually monitoring the plurality of timers for the plurality of stations associated with the multicast group; receiving an inbound frame from the first station associated with the multicast group; resetting the timer corresponding to the first station responsive to receiving the inbound frame; receiving a frame for the multicast group; waiting in accordance with the monitoring of the plurality of timers until all of the plurality of times have expired, indicating that all of the plurality of stations associated with the multicast group are in an active mode, wherein the first and second timers expire at different times; and transmitting the frame to the multicast group responsive to determining that all of the plurality of stations associated with the multicast group are in the active mode.
2. The method of power management for a network as in claim 1 , wherein the plurality of stations are contention free pollable.
3. The method of power management for a wireless network as in claim 2 , wherein the plurality of stations are in active mode when they are available for a contention free poll.
4. The method of power management for a network as in claim 1 , wherein a GARP Multicasting Registration Protocol is used to associate the plurality of stations with the multicast group.
5. The method of power management for a network as in claim 1 , wherein the transmitting of the frame occurs during a contention period.
6. The method of power management for a network as in claim 1 , further comprising waiting for an inbound packet from a wireless station immediately after sending the frame.
7. An access point, comprising: a wireless transceiver for communicating with a plurality of stations; a point controller that determines when to send data to the plurality of stations; wherein the point controller associates a first wireless station and a second wireless station into a multicast group, the first wireless station having a first power save interval corresponding to a first time period that the first wireless station is in a first power save state and unable to receive frames, and the second wireless station having a second power save interval corresponding to a second time period that the second wireless station is in a second power save state and unable to receive frames, wherein the first power save interval is independent of the second power save interval; wherein the point controller sets a first timer at a first time corresponding to the first power save interval when the first wireless station enters the first power save state and a second timer at a second time corresponding to the second power save interval when the second station enters the second power save state, wherein the first and second times are different; wherein the point controller resets the first timer to the first power save interval responsive to receiving an inbound frame from the first wireless station; wherein the point controller receives a multicast frame for the multicast group; wherein the point controller monitors the first timer and determines whether the first wireless station is in the first power save interval; wherein the point controller monitors the second timer and determines whether the second wireless station is in the second power save state; and wherein the point controller delivers the multicast frame to the first and second wireless stations associated with the multicast group, independent of a delivery traffic indication message beacon, upon determining the first timer and the second timer have expired, ensuring the first wireless station and the second wireless station are in active mode, wherein the first timer and second timer expire at different times that are not scheduled by the point controller.
8. The access point of claim 7 , wherein a GARP Multicasting Registration Protocol is used to associate the first wireless station and the second wireless station with the multicast group.
9. The access point of claim 7 , further comprising, the point controller reserving a wireless channel after the first timer expires; the point controller sending a unicast frame with a poll to the first station after the first timer expires; and the point controller waiting for a response for the poll.
10. The access point of claim 7 , wherein the access point is configured to wait a shorter time period than the first station and the second station to gain control of a channel coupling the access point to the first station and the second station.
11. The access point of claim 7 , wherein the point controller resets the second timer to the second power save interval responsive to receiving an inbound frame from the second wireless station.
12. The access point of claim 7 , further comprising a buffer; wherein the point controller stores the multicast frame in the buffer until the first timer and the second timer have expired responsive to determining that at least one of the first timer and second timer have not yet expired.
13. An access point, comprising: means for associating a first wireless station and a second wireless station into a multicast group, the first wireless station having a first power save interval corresponding to a first time period that the first wireless station is in a first power save state and unable to communicate, and the second wireless station having a second power save interval corresponding to a second time period that the second wireless station is in a second power save state and unable to communicate, wherein the first power save interval is independent of the second power save interval and time periods that the first and second wireless stations are in the first and second power save state are not synchronized; means for setting a first timer corresponding to the first power save interval responsive to the first wireless station entering the first power save state; means for setting a second timer corresponding to the second power save interval responsive to the second wireless station entering the second power save state; means for resetting the first timer to the first power save interval responsive to receiving an inbound frame from the first wireless station; means for receiving a frame for the multicast group; means for monitoring the first timer and determining whether the first wireless station is in the first power save interval based on whether the first timer has expired; means for monitoring the second timer and determining whether the second wireless station is in the second power save interval based on whether the second timer has expired; and means for immediately delivering the frame, independent of a delivery traffic indication message beacon, responsive to determining the first timer and the second timer have expired ensuring the first wireless station and the second wireless station are each in the active mode; wherein the first timer expires at a different time than the second timer.
14. An access point according to claim 13 , further comprising means for gaining control of a wireless channel using prioritized access for broadcasting the frame.
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November 21, 2005
April 17, 2012
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